Help growers kick grass weeds to the kerb

With weed control season for white clover coming up fast, it’s time to start talking to your growers about their options for keeping seed crops clean and high yielding.

That’s the advice from one of the country’s largest crop protection suppliers, which says the number and type of weeds covered by different herbicides is not the only thing to consider.

How these inputs support ongoing herbicide management strategies is also important, particularly in terms of removing grass weeds.

As a Group 3 benzamide herbicide, Kerb 500F from Corteva Agriscience has a different mode of action from other chemistry often used against grass weeds in white clover seed production, says technical specialist Nicole Morris.

“Use of Kerb is growing year on year. People are cottoning on to the fact that it is a really good resistance management tool and alternative to Group 1 herbicides.”

Kerb’s active ingredient is propyzamide, which works through root absorption to control unwanted species like annual poa, barley grass, soft brome and vulpia hair grass, as well as ryegrass.

“The recommended application window is from May through to August,” Morris explains. “Kerb controls germinating and seedling weeds after application.”

For best results, Kerb should be used when soil temperatures are declining (13°C or less), and when soil is moist, followed by 15–35 mm of either rainfall or irrigation after application, to wash the active ingredient into the root zone of target weeds.

Likewise, Morris recommends applying Kerb to bare ground, free from trash, to achieve good soil coverage and improve soil penetration.

“The other important thing to note about Kerb is that it is quite a slow-acting product, so it can take up to six weeks for growers to see the effect.”

Kerb is a residual herbicide, and treated areas should be ploughed and thoroughly cultivated before sowing following crops.

Generally, Kerb residues will have diminished to levels safe to following crops of grasses or cereals within eight to nine months.